Surfactants from long-chain carbon-containing molecules

ABSTRACT

Compositions of furan based surfactants derived from unsaturated carbon-containing molecules, such as fatty acids, as well as methods for forming furan based surfactants from unsaturated carbon-containing molecules, such as fatty acids, are disclosed herein. These compositions and methods can utilize long-chain (e.g., C14-C26) unsaturated carbon-containing molecules, for instance unsaturated fatty acids such as oleic acid or methyl oleate from soybean oil, to derive oleo-furan surfactants. To facilitate this, certain such embodiments include reaction steps that cleave the reactant molecule (e.g., methyl oleate) at the double bond and subsequently oxidize products to form a carboxylic acid molecule and a dicarboxylic acid molecule. In such embodiments, these two acids can be subsequently acylated with furan and functionalized to form surfactants.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/697,099 filed Jul. 12, 2018, the contents of which are herebyincorporated by reference.

TECHNICAL FIELD

This disclosure generally relates to compositions of furan basedsurfactants derived from long-chain carbon-containing molecules, such asunsaturated fatty acids, as well as methods for forming furan basedsurfactants from long-chain carbon-containing molecules, such asunsaturated fatty acids.

BACKGROUND

Surfactants are chemical compounds that have a variety of applications.Such applications can include household cleaners and detergents,institutional & industrial cleaning products, agricultural chemicalssuch as spray adjuvants, oilfield applications, and various coatingadditives. Short for surface active agent, a surfactant consists of ahydrophilic moiety, which attracts water, and a hydrophobic moiety,which attracts oil and dirt. The amphiphilic structure of surfactantmolecules enables them to suspend dirt, emulsify, and modify surfaceproperties of materials. Variations in the chemical structure of asurfactant molecule can enable tunable properties, such as emulsifyingcapability (hydrophilic/lipophilic balance), oil/dirt suspensioncapacity (critical micelle concentration), cold water performance(Krafft point), foaming, and biodegradation.

Surfactants have generally been synthesized from petrochemicalfeedstocks, such as long chain alkanes/alkenes and ethylene oxide.However, surfactants synthesized from petrochemical feedstocks canpresent a number of issues. For one, such surfactants include chemicalsthat can be harmful to the environment. Moreover, such surfactants maynot perform as intended in certain applications. For example, despitedecades of development, these various surfactant structures are faced bya unified problem—the presence of hard water (e.g., containing calcium,magnesium, iron, etc.) inactivates these surfactants. When inactivationoccurs, this causes surfactants to form solid precipitates andsubstantially lose the intended functionality.

To address these issues associated with surfactants synthesized frompetrochemical feedstocks, surfactants are beginning to be derived fromnatural sources, such as coconut oil and palm kernel. The developmenthas mainly focused on replacing the petrochemical surfactants withbio-based analogues having identical chemical structure (e.g., sodiumlauryl sulfate from petroleum and sodium coco sulfate from coconut oil).The result is a surfactant that is more eco-friendly relative topetrochemical surfactants. Moreover, to solve the problem of surfactantinactivation in the presence of hard water, a new class of bio-basedsurfactants, called oleo-furan surfactants (“OFS” or “OFSs”) has beendeveloped. In fact, OFSs have demonstrated 50-100 times greater calciumtolerance compared with other surfactants.

While OFSs solve issues associated with surfactants synthesized frompetrochemical feedstocks, the natural sources, such as coconut oil andpalm kernel, currently used to derive OFSs can be expensive to procure.As such, the use of these types of natural sources can hamper the valuesof OFSs because it can make it more difficult for OFSs to competeeconomically with the cost of petrochemical surfactants. Moreover, insome cases, the natural sources currently used to derive OFSs may needto be procured via methods that are less sustainable than may bedesired.

SUMMARY

Notably, up to this point, long-chain (e.g., C₁₄-C₂₆) carbon-containingmolecules, such as unsaturated fatty acids obtained from soybean oil,have been considered impractical as a source from which to synthesizeoleo-furan surfactants. Instead, up to this point, shorter chain fattyacids have generally been used to derive oleo-furan surfactants. But,the natural sources of these shorter chain fatty acids, like coconut oiland palm kernel, tend to be expensive to procure.

Various embodiments disclosed herein provide the ability to utilizelong-chain (e.g., C₁₄-C₂₆) unsaturated carbon-containing molecules toderive oleo-furan surfactants. Because certain such long-chain carbonmolecule sources may be more readily available, various embodimentsdisclosed herein may thereby allow oleo-furan surfactants to besynthesized from a more cost-effective natural source. This, in turn,may ultimately allow oleo-furan surfactants to be more economicallycompetitive with traditional petrochemical surfactants while stillproviding the eco-friendly and hard-water tolerance benefits ofoleo-furan surfactants over petrochemical surfactants.

In general, various exemplary embodiments disclosed herein include aprocess for synthesizing oleo-furan surfactant structures fromlong-chain (e.g., C₁₄-C₂₆) unsaturated carbon-containing molecules. Inaddition, various exemplary embodiments disclosed herein includesurfactant chemical structures synthesized by the disclosed reactionprocesses using long-chain (e.g., C₁₄-C₂₆) unsaturated carbon-containingmolecules.

For instance, some embodiments disclosed herein may synthesizeoleo-furan surfactant structures from long-chain (e.g., C₁₄-C₂₆)unsaturated carbon-containing molecules, such as unsaturated fatty acidsobtained from soybean oil. This can serve as an alternative to the notedshorter chain fatty acids (e.g., C₆-C₁₃), obtained from palm kernel orcoconut oil, used in prior OFS synthesis processes. Accordingly, certainprocess embodiments disclosed herein may differ from prior processes foroleo-furan surfactant synthesis processes because these embodimentsherein use a longer chain, unsaturated fatty acid such as oleic acid ormethyl oleate from soybean oil. To facilitate this, certain embodimentsdisclosed herein can include reaction steps that cleave the reactantmolecule (e.g., methyl oleate) at the double bond and subsequentlyoxidize products to form a carboxylic acid molecule and a dicarboxylicacid molecule. In such embodiments, these two acids can be subsequentlyacylated with furan and functionalized to form surfactants. Accordingly,such process embodiments disclosed herein can ultimately producesurfactant chemical compositions that are also within the scope of thepresent disclosure.

One exemplary embodiment includes a method of forming a surfactant. Thismethod can include a step of forming a fatty acid or methyl ester. Forinstance, this step could include forming oleic acid or methyl oleate.The fatty acid or methyl ester could be formed, for instance, by anesterification reaction. The formed fatty acid or methyl ester can havea chain length of C₁₄-C₂₆. The method can also include a step ofcleaving this reactant fatty acid, methyl ester, or triglyceridemolecule (e.g., oleic acid or methyl ester) at a double bond thereof andoxidizing the resulting products to form each of a carboxylic acidmolecule and a dicarboxylic acid. The method can further include thestep of acylating one or both of the carboxylic acid molecule and adicarboxylic acid by reacting each of the carboxylic acid moleculeand/or the dicarboxylic acid with furan or a furan-based molecule (e.g.,methylfuran). The method can additionally include the step offunctionalizing one or both of the acylated acids from the prior stepinto a surfactant by adding one or more hydrophilic functional groups.This step could be done, for example, via sulfonation.

Another exemplary embodiment includes a surfactant composition accordingto any one of the following examples, where the alkyl chain lengthbetween furan molecules can vary, for instance, from n=0 to n=24:

The details of one or more examples are set forth in the accompanyingdrawings and description below. Other features, objects, and advantageswill be apparent from the drawings and description.

BRIEF DESCRIPTION OF DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and, therefore, do not limit the scope of theinvention. The drawings are intended for use in conjunction with theexplanations in the following description. Embodiments of the inventionwill be described in conjunction with the appended drawings, whereinlike reference characters denote like elements.

FIG. 1 is a flow diagram of an embodiment of a method of forming asurfactant from long-chain unsaturated carbon-containing molecules.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description provides somepractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of elements, materials, compositions, and/orsteps are provided below. Though those skilled in the art will recognizethat many of the noted examples have a variety of suitable alternativesthat are also within the scope of the present disclosure.

As described herein, embodiments of the present disclosure can utilizelong-chain (e.g., C₁₄-C₂₆) carbon-containing molecules, such asunsaturated fatty acids obtained from soybean oil, to derive oleo-furansurfactants. In this way, embodiments of the present disclosure canutilize a more readily available natural source to produce a morecost-effective oleo-furan surfactant.

One exemplary embodiment of a synthesis process is depicted below asScheme 1. Scheme 1 illustrates an exemplary reaction for synthesis ofmono- and di-anionic oleo-furan surfactants from fatty acids ortriglycerides. Subscripts ‘m’ and ‘n’ are used in Scheme 1 to designatealkyl chains of variable length.

The exemplary embodiment shown in Scheme 1 includes cleavage of a doublebond followed by oxidation to generate two compounds: (1) acarbon-containing molecule with a carboxylic acid and (2) acarbon-containing molecule with two carboxylic acids.

The resulting two molecules are then acylated with an aromatic molecule,such as furan, to form two general molecules. These two generalmolecules are shown below as General Structure 1 and General Structure2, where each numbered position 1-6 designates a functional group, suchas —H, —CH3, —CH2CH3, a longer alkyl chain, —OH, or other functionalgroup, and ‘n’ designates an extended saturated alkyl chain 0-24 carbonsin length.

To form various surfactant molecules, subsequent reactions can then beperformed on one of General Structure 1 and General Structure 2, both ofGeneral Structure 1 and General Structure 2, or a resulting mixture ofGeneral Structure 1 and General Structure 2.

For example, one optional subsequent reaction is the reduction of theketone moieties on General Structure 1 and General Structure 2 to formfully reduced group (e.g. hydrocarbon). The resulting structures fromthis optional subsequent reaction are shown below as General Structure 3and General Structure 4.

In a further example, an additional option is to partially reduce theketone functional groups to an alcohol.

Then, to functionalize any of General Structure 1, General Structure 2,General Structure 3, and/or General Structure 4 into a surfactant, oneor more hydrophilic functional groups can be added to any combination ofthe numbered positional designations 1, 2, 3, 4, 5, and/or 6. Forinstance, in various embodiments examples of such functional groups caninclude sulfates, sulfonates, alcohols, ethoxylates, propoxylates,amines, or other functional groups listed in Table 1 and Table 2 shownbelow. In particular, Table 1 shows examples of ionic moieties that makeup the hydrophilic portion of the surfactant in any one or more ofGeneral Structure 1, General Structure 2, General Structure 3, andGeneral Structure 4. Table 2 shows examples of non-ionic moieties thatmake up the hydrophilic portion of the surfactant in any one or more ofGeneral Structure 1, General Structure 2, General Structure 3, andGeneral Structure 4.

TABLE 1 Ionic Moieties Anionic Cationic Sulfate

Amines & Ammonium salts

Sulfonate

Sulfinate

Thiosulfate

Polyammonium

Sulfamidate

Hydroxyammonium

Carboxylate

Pyridinium

Sarcosinate

Pyridinium

Taurate

Imidazolinium

Phosphate

Benzimidazolinium

Oxonium

Pryphosphate

Sulfonium

Phosphonate

Phosphonium

Counter-ion Na⁺, K⁺, Li⁺, Ca²⁺, Mg²⁺, NH₄ ⁺, amines Cl⁻, Br⁻, NO₃ ⁻, SO₄²⁻, PO₄ ³⁻, HPO₄ ²⁻, H₂PO₄ ⁻, CH₃OSO₃ ⁻, HCO₂ ⁻, CH₃CO₂ ⁻

TABLE 2 Non-ionic moieties Polyethoxylate R—(—OCH₂CH₂—)_(n)—ORPoly(Oxyethylene-co-Oxypropylene) 1

2

1,4-Sorbitan derivatives

Isosorbide derivatives

Polyglycoside

As an example of such functionalization into a surfactant, in oneembodiment a monounsaturated fatty acid, such as oleic acid derived fromsoybean, is used to synthesize a surfactant. Alternately, a distributionof fatty acids with varying alkyl chain length and varying degrees ofunsaturation could be used, such as those obtained from soybean oil.Formation of methyl oleate can be achieved by esterification of oleicacid or transesterification directly from a triglyceride. Theunsaturated methyl ester can then be cleaved at the double bond locationto form a fatty acid and a dicarboxylic acid. Both molecules can besubsequently acylated with furan, optionally reduced to remove theketone functional groups, and functionalized with a hydrophilic groupsuch as a sulfonate.

Scheme 2 is shown below and illustrates an exemplary embodiment of sucha functionalization reaction scheme for synthesis of mono- anddi-anionic oleo-furan surfactants from oleic acid or methyl oleate.Subscript ‘7’ is used in Scheme 2 to designate a hydrocarbon repeatchain with a length of seven carbons.

The following description provides exemplary details relating to stepsin the disclosed embodiment shown as Scheme 2.

As disclosed above, Scheme 2 can include a reaction to form a fatty acidmethyl ester, such as methyl oleate. If starting with a triglyceride,fatty acid methyl esters can be obtained via a transesterificationreaction with methanol. If starting with a fatty acid, an esterificationreaction can be performed to form a methyl ester, which may be achievedby mixing the fatty acid with hydrochloric acid in methanol solution.

As also disclosed above, in Scheme 2 this unsaturated methyl ester canbe cleaved at the double bond location to form a fatty acid and adicarboxylic acid. This can be accomplished, for instance, using analkene cleavage reaction.

Scheme 3 is shown below and illustrates an exemplary embodiment ofolefin metathesis and oxidation of fatty methyl esters.

For example, as shown in the embodiment of Scheme 2, the alkene of theresulting methyl ester can be cleaved to the dicarboxylic andmonocarboxylic acid moieties by means of ozonolysis of compound in thepresence of oxidizing agents including, for example, but not limited to,hydrogen peroxide. Oxidative cleavage of the alkene to carboxylic acidscan also be achieved using inorganic and organometallic catalysts andreagents, including, for example, but not limited to, iron nitrate,metal organic frameworks, polyoxymetallates, zinc, osmium tetrachloride,Jones reagent (CrO₃/H₂SO₄), manganese porphyrin complexes, indiumtrichloride, and ruthenium trichloride, using oxidants including, forexample, but not limited to, molecular oxygen, inorganic acids such assulfuric acid, organic oxidants such as tert-butyl hydroperoxide,hydrogen peroxide, oxone, and inorganic salts such as sodium periodateand potassium permanganate.

As shown in the embodiment of Scheme 3, alternatively the alkenecleavage can be achieved by means of olefin metathesis to yield twoterminal alkenes moieties, followed by oxidation to yield thedicarboxylic and monocarboxylic acids. Catalysts for the olefinmetathesis include, for example, but are not limited to, transitionmetal alkylidine complexes and zeolite-supported transition metaloxides. The subsequent oxidation of the terminal alkenes can be achievedby ozonolysis or with oxidation catalysts/reagents, for instance similarto those listed above for alkene oxidation.

Scheme 4 is shown below and illustrates an exemplary embodiment ofcarbonylation of fatty methyl ester olefin metathesis products:

As shown in the embodiment of Scheme 4, after alkene cleavage by olefinmetathesis to yield two terminal alkenes moieties, the two terminalalkenes can be carbonylated as an alternative to oxidation,incorporating two equivalents of CO₂ to yield the dicarboxylic andmonocarboxylic methyl esters which may subsequently be deprotected toyield the dicarboxylic and monocarboxylic acids. Catalysts for thecarbonylation include, for example, but are not limited to, palladiumcatalysts such as palladium hydride and ruthenium catalysts includingruthenium carbonyl complexes. Cocatalysts include, but are not limitedto, acidic catalysts such as toluenesulfonic and methanesulfonic acid.Sources of CO₂ include, but are not limited to, gaseous CO₂ and CO,organic CO surrogates such as aldehydes and formates, and inorganic COsources such as metal carbonyl complexes.

The methyl esters present after metathesis and alkene oxidation reactionpathway (Scheme 3) as well as in the metathesis and carbonylationreaction pathway (Scheme 4) can be deprotected to provide thedicarboxylic and monocarboxylic acid moieties with a method analogous toScheme 2 above. The dicarboxylic and monocarboxylic acids cansubsequently be used for the acylation of a furan moiety to yieldalkyldifuran and alkylfuran compounds of General Structure 1 and 2,respectively. As is also analogous to Scheme 2 above, reduction of theacylated compounds of General Structure 1 and 2 can yield products ofthe General Structure 3 and 4, respectively.

Scheme 5 is shown below and illustrates an exemplary embodiment ofdecarboxylation and the subsequent carbonyl-ene or arylation reactivityof fatty methyl ester metathesis products.

As shown in the embodiment of Scheme 5, after alkene cleavage by olefinmetathesis to yield two terminal alkenes moieties, the two terminalalkenes can be decarboxylated as an alternative to oxidation andcarbonylation, removing one equivalent of carbon dioxide from the methylester and resulting in two hydrocarbon chains with only terminal alkenefunctional groups. Subsequent reaction of the alkenes with twoequivalents of a furan-based aldehyde, including but not limited tofurfural, in a carbonyl-ene reaction yields two alkyl furan moietieswith alcohol functional groups positioned adjacent to the furan ring.Alternatively, arylation of the terminal alkenes with a furan moiety,including but not limited to furan and methyl furan, can yieldalkylfuran products of General Structure 4. Catalysts for thedecarboxylation include, for example, but are not limited to, metalcoordination complexes such as Ru₃(CO)₁₂, supported metal catalysts suchas Ni, Co, Cu, Pd, and Pt on such supports as carbon, metal oxides, andmixed metal oxides. Catalysts for the carbonyl-ene reaction include, butare not limited to, metal coordination complexes such as Ni[COD]₂ andNi[PPh₃]₂. Catalysts for the arylation of terminal alkenes include, butare not limited to, Pd, Cu, and Ni coordination complexes such asNi[COD]₂ and Ni

-heterocyclic carbine complexes (Ni[NHC]) or the analogousarene-coordinated complexes (Ni[NHC]arene).

Another possible embodiment of the carbonyl-ene reaction seen in Scheme5 can be seen in Scheme 6 below, in which the terminal alkenes generatedby metathesis and subsequent decarboxylation then undergo a carbonyl-enereaction with a molecule containing two aldehydes, including but notlimited to 2,5-furandicarbaldehyde, to produce a dialkylfuran compoundwith alcohol functional groups positioned adjacent to the furan ring.

The resulting alkylfuran and dialkylfuran products seen in Schemes 5 and6 are embodiments of General Structures 5 and 6, respectively, as shownbelow.

As with General Structures 1-4, to make General Structure 5 and/or 6,into a surfactant, one or more hydrophilic functional groups can beadded to any combination of the numbered positional designations 1, 2,and/or 3. For instance, in various embodiments examples of suchfunctional groups can include sulfates, sulfonates, alcohols,ethoxylates, propoxylates, amines, or other functional groups listed inTable 1 and Table 2 shown below. In particular, Table 1 shows examplesof ionic moieties that make up the hydrophilic portion of the surfactantin any one or more of General Structure 5 and General Structure 6. Table2 shows examples of non-ionic moieties that make up the hydrophilicportion of the surfactant in any one or more of General Structure 5 andGeneral Structure 6.

Schemes 7 and 8 are shown below and illustrate an exemplary embodimentof such a functionalization reaction scheme for synthesis ofmono-anionic and non-ionic oleo-furan surfactants from compounds ofGeneral Structure 5 and 6, respectively.

As disclosed above, Schemes 2, 3, and 4 can include a deprotectionreaction. For instance, deprotection of the methyl ester moiety can beachieved by mixing the compound with an inorganic base, including, forexample, but not limited to, sodium hydroxide or potassium hydroxide, inan aqueous, alcohol, or other suitable solvent.

As also disclosed above, Scheme 2, 3, and 4 can include the acylation offuran with fatty acid anhydrides. As one such example, the carboxylicacid and/or dicarboxylic acid can be reacted with furan or a furan-basedmolecule (e.g. methylfuran) in a heated, pressurized reactor system witha solid catalyst, such as a solid acid zeolite catalyst. One suchexample of this type of reaction is described in InternationalPublication No. WO 2017/079719, the contents of which are herebyincorporated by reference.

Furthermore, as disclosed above, Schemes 2, 7, and 8 can optionallyinclude the reduction of the acylated product. For example, thisoptional step in the process to form an alternate surfactant structurecan include reducing the ketone functional groups attached to the carbonadjacent to furan. This can be done in the presence of hydrogen gas atelevated temperature and pressure and in the presence of a solidcatalyst, such as copper chromite. Additional examples of a reduction ofthe acylated product are described in the above referenced andincorporated International Publication No. WO 2017/079719.

Finally, as disclosed above, Schemes 2, 7, and 8 can include asulfonation reaction. For example, sulfonation of the reduced ornon-reduced surfactant precursor can be performed at scale via thepreviously developed SO₃-air reaction or via other suitable sulfonationmethods, such as SO₃-pyridine.

As noted, one or more of the described reaction steps in Scheme 2 canuse one or more catalysts. Such reaction steps in Scheme 2 can includethe acylation and reduction reactions. When a catalyst is implemented,the reactions can be carried out using any of the catalysts listed inTable 3 shown below. Table 3 shows exemplary catalyst classes along withassociated types that can be used for any one or more (e.g., all) of thereactions in Scheme 2.

TABLE 3 Family Genus Species Example Acid Lewis L-Acid AlCl₃, TiCl₄,FeCl₃, BF₃, SnCl₄, Acid ZnCl₂, ZnBr₂, Amberlyst-15 (L-Acid) SupportedL-Acid SiO₂, Al₂O₃, ZrO₂, Catalysts L-Acid/S TiO₂, SiO₂—Al₂O₃ BrØnstedB-Acid HCl, HBr, HI, HClO₄, HClO₃, Acid HNO₃, H₂SO₄, CH₃COOH, (B-Acid)CF₃COOH, H₃PO₄ Catalysts Solid Zeolites, (Z) H-ZSM-5, H-BEA, H-Y, AcidMordenite, Ferrierite Catalysts Substituted- Sn, Ge, Ti, Fe, Zr Zeolites(Sub.) Heteropolyacids H₃PW₁₂O₄₀, H₃SiW₁₂O₄₀, (HPAs) H₃PMo₁₂O₄₀,H₃SiMo₁₂O₄₀ (Cs⁺ substituted HPAs) Phosphate Niobium phosphate (NbOPO₄),(PO4³⁻) Zirconium phosphate (ZrO₂—PO₄), Siliconiobium phosphate(Nb—P—Si—O) Zirconia (ZrO₂) SO₃—ZrO₂, SiO₂—ZrO₂, Zeolites-ZrO₂,Al₂O₃—ZrO₂, WO_(x)—ZrO2 Carbon (C) Sulfated carbon (SO₃H-functionalizedcarbon) Base Solid Supported KF/Al₂O₃, K₂CO₃/Al₂O₃, KNH₂/ Base AlkalisAl₂O₃, NaOH/Al₂O₃, KOH/ Catalysts Al₂O₃ Zeolites, Clays K, Rb,Cs-exchanged X-zeolites, ETS-10, Sepiolite, Phosphates Hydroxyapatite,natural phosphates Amides, imines, KNH₂/Al2O3, K, Y, Eu amines, orsupported on zeolites ammonium ions on support Metal Oxide, MgO, CaO,Mg—Zr—O, Mixed Metal Mg—Si—O, Mg—Al—O, ZrO₂, Oxide SiO₂, TiO₂, CrO₃,Al₂O₃, WO₃/ ZrO₂, CeO₂ Homo- Organic & pyridine, imidazole, ammoniageneous Inorganic Base Metal Metallic Precious metals, Pt, Pd, Ni, Cu,Al, alkali or alkaline Zn, Au, Ag, Sn, Co earth metals BimetallicTransition-Transi- Pd—Cu, Cu—Ni, Cu—Cr, tion or Precious- Ni—Pt, Ni—Pd,Ni—Sn Transition metals Metal Metal oxides, NiO, ZnO₂, CuO, Cu—Cr—O,Oxide Rare earth oxides, Cu—Ni—O, Cu—Al—O, Al₂O₃, Alkali metal ZrO₂,La₂O₃ oxides Metal Metal carbonyls, Ru₃(CO)₁₂, Ni[COD]₂, Ni[PPh₃]₂ Coor-Metal phosphines, dination Organometallic Complex complexes SupportedMetals supported Pt, Pd, Ni, Cu, Al, Zn, Au, Ag, Metal on metal oxides,Sn, Co supported on MgO, CaO, mixed metal Mg—Zr—O, Mg—Si—O, oxides,zeolites, Mg—Al—O, ZrO₂, SiO₂, TiO₂, carbon CrO₃, Al₂O₃, WO₃/ZrO₂, CeO₂,C

Also with respect to the reaction steps in Scheme 2, various feedstockmaterials and solvents can be used. Feedstocks used in the process caninclude, for example, but are not limited to fatty acids or fatty acidmethyl esters with chain lengths varying from (C₃ to C₂₆), triglyceridesboth mixed and homotriglycerides with chains lengths varying from (C₃ toC₂₆) and can be saturated or unsaturated (mono-, di-, or tri-), furan orfuran derivatives such as methylfuran, ethylfuran, or furfural,trifluoroacetic anhydride, acetic anhydride, and solvents.

Solvents used for separations in an embodiment of the described processcan be, for instance, ketones including acetone and methylethylketone,hydrocarbons including, but not limited to pentane, hexane, and heptane,cyclohexane, and cyclopentane, aromatic organics including benzene,toluene, organic nitriles including acetonitrile, propionitrile, andbutyronitrile, organic chlorocarbons including dichloromethane,dichloroethane, chloroform, alcohols including, but not limited to,methanol, ethanol, and isopropanol, ethereal solvents including, but notlimited to, dimethyl ether, diethyl ether, and tetrahydrofuran, estersincluding, but not limited to, methyl acetate and ethyl acetate, andwater. Though it is also noted that one or more separations in processembodiments can be accomplished in the absence of solvent (i.e. neat).

In some embodiments, solvent use will be limited by one or more solventselection guides. For example, in some embodiments, solvent use will belimited by one or more solvent selection guides outlined in Byrne, F.P., et al., Tools and Techniques for Solvent Selection: Green SolventSelection Guides, Sustainable Chemical Processes 2016 4(7). Suchsolvents may include, though are not limited to, acetone, heptane,cyclohexane, toluene, xylene, acetonitrile, methanol, ethanol,isopropanol, 1-butanol, ethyl acetate and isopropyl acetate, cyclopentylmethyl ether, 2-methyltetrahydrofuran, tetrahydrofuran, and water.Though it is also noted that this could instead occur in the absence ofsolvent (i.e. neat). In one particular embodiment, solvent use will belimited to those accepted by all solvent selection guides outlined inByrne, F. P., et al., Tools and Techniques for Solvent Selection: GreenSolvent Selection Guides, Sustainable Chemical Processes 2016 4(7). Suchsolvents including 1-butanol, isopropyl acetate, and water. Though,again, it is noted that this could instead occur in the absence ofsolvent (i.e. neat).

FIG. 1 shows a flow diagram of an embodiment of a method 100 of forminga surfactant from long-chain unsaturated carbon-containing molecules.The method 100 can include one or more of the synthesis actionsdescribed previously.

At step 110, the method 100 includes cleaving a long-chain unsaturatedcarbon-containing molecule to generate a carbon-containing molecule. Forinstance, in one example, the long-chain unsaturated carbon-containingmolecule has a chain length of C14 to C26. In one example, thelong-chain unsaturated carbon-containing molecule with this chain lengthis a long-chain unsaturated fatty acid or one of oleic acid and methyloleate. For instance, the long-chain unsaturated carbon-containingmolecule cleaved to generate the carbon-containing molecule can be along-chain unsaturated fatty acid derived from soybean oil. In oneexample, cleaving the long-chain unsaturated carbon-containing moleculeto generate the carbon-containing molecule can include an olefinmetathesis. At step 110, the long-chain unsaturated carbon-containingmolecule can be cleaved, for instance, at a double bond of thelong-chain unsaturated carbon-containing molecule to generate thecarbon-containing molecule.

In one particular embodiment, prior to cleaving a long-chain unsaturatedcarbon-containing molecule at step 110, the method 100 can includeesterification of oleic acid to form methyl oleate. This methyl oleatecan be the long-chain unsaturated carbon-containing molecule cleaved togenerate the carbon-containing molecule at step 110. In anotherparticular embodiment, prior to cleaving a long-chain unsaturatedcarbon-containing molecule at step 110, the method 100 can includetransesterification of a triglyceride with methanol to form methyloleate. This methyl oleate can be the long-chain unsaturatedcarbon-containing molecule cleaved to generate the carbon-containingmolecule at step 110.

At step 120, the method 100 includes oxidizing the carbon-containingmolecule to form at least one of a monocarboxylic acid molecule and adicarboxylic acid molecule. For instance, in one example, oxidizing thecarbon-containing molecule forms each of a monocarboxylic acid moleculeand a dicarboxylic acid molecule. In one example, oxidizing thecarbon-containing molecule to form at least one of a monocarboxylic acidmolecule and a dicarboxylic acid molecule can include ozonolysis of thecarbon-containing molecule in the presence of hydrogen peroxide.

At step 130, the method 100 includes acylating the at least one of themonocarboxylic acid molecule and the dicarboxylic acid molecule with afuran-based molecule to form a furan compound. For instance, in theexample where oxidizing the carbon-containing molecule forms each of amonocarboxylic acid molecule and a dicarboxylic acid molecule, each ofthe monocarboxylic acid molecule and the dicarboxylic acid molecule canbe acylated with the furan-based molecule to form the furan compound. Inone example, the furan-based molecule is one of furan and methylfuran.

At step 140, the method 100 includes forming a surfactant from the furancompound. In one example, the surfactant formed from the furan compoundcan be an oleo-furan surfactant. For instance, at step 140, thesurfactant can be formed from the furan compound by functionalizing thefuran compound with a hydrophilic group, as described elsewhere herein.

As indicated previously, embodiments disclosed herein can includesurfactant chemical compositions. Such surfactant chemical compositionscan result from the reactions for forming furan based surfactants fromunsaturated fatty acids disclosed herein. For example, varioussurfactant chemical compositions can be derived from long-chain (e.g.,C₁₄-C₂₆) unsaturated carbon-containing molecules, such as unsaturatedfatty acids obtained from soybean oil.

Described and illustrated above was General Structure 1. GeneralStructure 1 can be part of a class of di-furan surfactants having furanmoieties on both ends of the alkyl chain. In General Structure 1, thealkyl chain length between furan molecules can vary from n=0 to n=24,while functional groups designated by numbers 1-6 can be —H, —CH3,—CH2CH3, a longer alkyl chain, —OH, sulfonate, sulfate, amine, oranother functional group listed in Table 1 or Table 2. Depicted beloware Structure 1A and Structure 1B. Structure 1A and Structure 1B areeach one example of a structure that adheres to the more general formulaof General Structure 1. Depending on the particular application forwhich a surfactant is intended to be used, Structure 1A and Structure 1Bcan be preferred structures embodying the general formula of GeneralStructure 1.

Also described and illustrated above was General Structure 3. GeneralStructure 3 can be part of a class of di-furan surfactants having furanmoieties on both ends of the alkyl chain. In General Structure 3, thealkyl chain length between furan molecules can vary from n=0 to n=24,while functional groups designated by numbers 1-6 can be —H, —CH3,—CH2CH3, a longer alkyl chain, —OH, sulfonate, sulfate, amine, oranother functional group listed in Table 1 or Table 2. Depicted beloware Structure 3A and Structure 3B. Structure 3A and Structure 3B areeach one example of a structure that adheres to the more general formulaof General Structure 3. Depending on the particular application forwhich a surfactant is intended to be used, Structure 3A and Structure 3Bcan be preferred structures embodying the general formula of GeneralStructure 3.

Additionally, General Structure 2 and General Structure 4 were describedand illustrated above. Examples of structures that adhere to GeneralStructure 2 and General Structure 4 can be found in the above referencedand incorporated International Publication No. WO 2017/079719.

Example

The following provides one illustrative, non-limiting example of asynthesis method and related synthesized structure.

Depicted below is a structure of Example Surfactant 1.

Example Surfactant 1 shown here is a dianionic bridged furan surfactantaccording to Structure 3A shown and described above. In synthesizingExample Surfactant 1, the acylation of two equivalents furan (>99%,Sigma) with dodecanoic acid (99%, Alfa Aesar) was carried out in hexanesolvent (Alfa Aesar) under ambient atmosphere and elevated temperaturein the presence of trifluoroacetic anhydride (Alfa Aesar) catalyst.Reduction of the ketone functionalities was performed in a batch reactorat elevated temperature pressurized with hydrogen. The reaction wasfacilitated with toluene solvent (99%, Alfa Aesar) and copper chromitecatalyst (Sigma). Finally, sulfonation of the surfactant precursor wascarried out under ambient atmosphere with elevated temperature inacetonitrile solvent (99.8%, Sigma) using pyridine sulfur trioxide (AlfaAesar) as the sulfonating agent. While this method of synthesis isprovided for exemplary purposes to illustrate one specific embodiment,those skilled in the art will appreciate that a number of variousalternative synthesis methods can be used within the scope of thepresent disclosure. For example, one or more synthesis procedures can beused as described in the above referenced and incorporated InternationalPublication No. WO 2017/079719.

Example Surfactant 1, shown above, has had certain performancecharacteristics assessed. For instance, performance of the synthesizedExample Surfactant 1 was measured via critical micelle concentration(CMC). The CMC was measured to be 1790 parts per million (ppm),equivalent to 3.54 mmol/L. Additionally, the Krafft point, or thetemperature below which the surfactant forms a solid precipitate wasmeasured to be below room temperature (22° C.). The tolerance of ExampleSurfactant 1 to calcium ions in solution was measured to identifysurfactant performance in hard water conditions. The calcium tolerance,defined as the Ca⁺⁺ concentration at which the surface tension is nolonger at a minimum or a visual precipitate is observed, was measured tobe greater than 60 mmol/L.

Various examples have been described with reference to certain disclosedembodiments. The embodiments are presented for purposes of illustrationand not limitation. One skilled in the art will appreciate that variouschanges, adaptations, and modifications can be made without departingfrom the scope of the invention.

1. A method of forming a surfactant, the method comprising: cleaving along-chain unsaturated carbon-containing molecule to generate acarbon-containing molecule; oxidizing the carbon-containing molecule toform at least one of a monocarboxylic acid molecule and a dicarboxylicacid molecule; acylating the at least one of the monocarboxylic acidmolecule and the dicarboxylic acid molecule with a furan-based moleculeto form a furan compound; and forming a surfactant from the furancompound.
 2. The method of claim 1, wherein the long-chain unsaturatedcarbon-containing molecule has a chain length of C₁₄ to C₂₆.
 3. Themethod of claim 2, wherein the long-chain unsaturated carbon-containingmolecule is a long-chain unsaturated fatty acid.
 4. The method of claim2, wherein the long-chain unsaturated carbon-containing molecule isselected from the group consisting of: oleic acid and methyl oleate. 5.The method of claim 1, wherein oxidizing the carbon-containing moleculeforms each of a monocarboxylic acid molecule and a dicarboxylic acidmolecule, and wherein each of the monocarboxylic acid molecule and thedicarboxylic acid molecule are acylated with the furan-based molecule toform the furan compound.
 6. The method of claim 1, wherein thefuran-based molecule is selected from the group consisting of: furan andmethylfuran.
 7. The method of claim 1, further comprising:esterification of oleic acid to form methyl oleate, and wherein methyloleate is the long-chain unsaturated carbon-containing molecule cleavedto generate the carbon-containing molecule.
 8. The method of claim 1,further comprising: transesterification of a triglyceride with methanolto form methyl oleate, and wherein methyl oleate is the long-chainunsaturated carbon-containing molecule cleaved to generate thecarbon-containing molecule.
 9. The method of claim 1, wherein cleavingthe long-chain unsaturated carbon-containing molecule to generate thecarbon-containing molecule comprises an olefin metathesis.
 10. Themethod of claim 1, wherein oxidizing the carbon-containing molecule toform the at least one of a monocarboxylic acid molecule and adicarboxylic acid molecule comprises ozonolysis of the carbon-containingmolecule in the presence of hydrogen peroxide.
 11. The method of claim1, wherein the surfactant formed from the furan compound is anoleo-furan surfactant.
 12. The method of claim 1, wherein the surfactantis formed from the furan compound by functionalizing the furan compoundwith a hydrophilic group.
 13. The method of claim 1, wherein thelong-chain unsaturated carbon-containing molecule is cleaved at a doublebond of the long-chain unsaturated carbon-containing molecule.
 14. Themethod of claim 1, wherein the long-chain unsaturated carbon-containingmolecule cleaved to generate the carbon-containing molecule is along-chain unsaturated fatty acid derived from soybean oil. 15-20.(canceled)